Medicinal specialists, who are the followers of the herbalism gods Osanyin and Erinle, use iron staffs with multiple bird images in their battles against witches. The Yoruba believe witches are the cause of illness, and a person who is afflicted must therefore seek help from someone who has influence in the spirit world. Paradoxically, the bird is the symbol of the witch, or "night birds" who come out after dark to work their evil. This marvelous staff serves as both a talisman, or protective charm, and as a symbol of authority. Sixteen small birds encircle a large central bird, seen as the embodiment of the god Ifa. This arrangement has been interpreted as, "a metaphor for the control of deadly power of the human mind". The number of birds is fundamental to Yoruba numerology, and is also the original number of Yoruba kings. The concentric unity gives the impression of continuous motion, of energy that is ceaseless and yet highly controlled. The large bird holds the balance together, perched on the slim staff which is both delicate and very strong at once. Unlike Western abstract art, this staff is imbued with meaning as part of an ancient culture, whose mysteries we may never completely understand.